Atoms STAAR Test

A chemist is identifying the elements found in a sample of pond water. What characteristic of an element's atoms always determines the identity of the element?

• Number of protons

• Number of neutrons

• Location of valence electrons

• Number of valence electrons

A student is studying sodium, a highly reactive metal that humans need to regular water balance in their bodies. Which characteristic of sodium is most closely related to its chemical reactivity?

• The 11 protons in each atom of sodium

• The density of sodium, which is 0.971 g/cm³

• The atomic mass of sodium, which is 22.990 amu

• The 1 valence electron in each atom of sodium

How many valence electrons are in an atom of each element in Group 13 in the Periodic Table?

• 13

• 3

• 10

• 5

Which table was completed correctly?

• A

• B

• C

• D

Students were asked to identify the location of elements in the periodic table based on clues prints on game cards.

Based on the data, which periodic table shows the correct location of the four elements?

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Which pair of properties describes the elements in Group 1?

• They are chemically stable and liquid at room temperature

• They have 1 valence electron and are not very reactive

• They are magnetic and boil at low temperatures

• They are solids at room temperature and highly reactive

Students in a science class prepared flashcards so that they could quiz one another about the arrangement of the Periodic Table. One of the flash cards contained information about two elements, Element L and Element M.

The students had to use the information on the flash card to determine possible positions of the two elements on a blank periodic table.

Which periodic table has the elements placed in locations that match the information on the flash card?

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An atom of an element contains 20 protons. What is the identity of the element? (8.5B)

• Argon

• Calcium

• Neon

• Potassium

Tags

NGSS.MS-PS1-1

If an element is shiny, can be hammered into thin sheets, and is a good conductor of electricity, what type of element is it? (6.6A)

• a metal

• a metalloid

• a non-metal

• a gas

Which of the following elements is MOST reactive? (6.6A)

• Fr

• Ca

• O

• Ba